Power operated staplers are known in the form of pneumatic and electrically powered devices. Such staplers are used for fastening in construction tools, and in the case of office type staplers, for binding papers. Powered office staplers are normally of the electric variety. Within the electric category common types are reduction gear driven by a motor, and impact driven through a solenoid. Gear driven types usually operate relatively slowly through cam or lever means. The slow operation allows a low peak electric current, for example through battery power or an alternate source of DC power from a line powered low voltage adaptor. An impact system through solenoid operates quickly, but requires high peak power, sometimes high enough to dim lights in an office setting. Further, the solenoid is expensive and bulky, including a large heavy copper winding. A further type of gear operated stapler uses the motor power to store energy in a spring, whereby the spring drives a staple by impact blow. However, these have required bulky structures.
In gear driven types, the amount of gear reduction required relates to the available power of the motor and the stapling energy required. A further important variable is the efficiency of the design. In some known prior designs there is substantial friction. Also in a design without spring energy storage the motor must drive through large changes in torque as the stapling cycle proceeds. As a minimum the gear reduction or motor size must allow for the peak forces of the cycle. This necessarily means the motor will operate well outside its peak efficiency loads or speeds for much of the cycle. A common such stapler may have four gear reduction stages to drive through such a cycle. A gear reduction device is also relatively slow typically requiring most of a full cycle to complete before the fastener is ejected. Further, the slow action makes such designs ill suited for use in construction tools since there is no anvil to press; the staple ejects too slowly to penetrate a wood or like surface.
In desktop use, pressing paper against or actuating a switch, or equivalent sensor, near the front of the stapler normally actuates the stapler. Commonly, the switch is to one side of the stapler. This facilitates manufacture of the device but leads to a loss of function—the actuation becomes sensitive to the angle in which papers are inserted. If the papers are angled toward the side with the switch, then the staple is installed too close to the edge of the page. If the angle is away from the switch, whereby the paper edge contacts an edge of the device opposite the switch, there may be no staple operation at all since the papers are obstructed from moving against the switch. The above-described behavior is a source of familiar unpredictability of operating electric staplers.
Some electric staplers allow for moving the position of the switch to change the location of the staple relative to the paper edge. The conventional side mounted switch is a known method to provide an adjustable switch position since it is known how to fit it beside the staple track in the various positions.
A common structure for an electric stapler includes an internal metal support frame and a separate external housing to form at least in part a double walled construction. With the support and enclosure functions separate, the overall size necessarily is large. For example, it is common that the external housing remains stationary while the internal frame moves down toward the anvil during a cycle. This requires ever more bulk to provide such movable mountings. Such a structure is complex and expensive. The very large housing is necessarily plastic to keep cost and weight reasonable. But such a large plastic structure often feels of low quality and amplifies noise.